Fig. 2. Task design and results for the reversal learning task.

a In each trial, one of two stimuli (a house and a landscape) was selected by the computer (indicated by a white frame) and participants had to predict whether the selected stimulus was associated with a reward (a happy smiley) or with punishment (a sad smiley). After participants’ prediction, the outcome was presented. Stimulus–outcome associations reversed after variable numbers of correct predictions. b D1R stimulation had no impact on predictions of the correct outcome following reversal trials with unexpected rewards. c Following unexpected punishment, increasing D1R activation improved behavior selectively in individuals with low baseline WMC.